Cardiovascular diseases and sudden cardiac arrest are a leading cause of death in North America. It is estimated by the American Heart Association that approximately 325,000 Americans die every year in cardiac events before they reach a hospital.
The technique of Cardio Pulmonary Resuscitation (CPR) was developed to allow for medical personnel and bystanders to treat persons suffering from sudden cardiac arrest. Standard CPR techniques require the delivery of both emergency breaths and chest compressions to the unconscious patient.
Original techniques for rescue breathing involve the use of mouth-to-mouth resuscitation. While mouth-to-mouth is a commonly known procedure for rescue breathing, it has several drawbacks. First, it requires the mouth of the person performing the procedure to come in direct physical contact with the mouth of the patient, which can cause the spread of disease. Second, it requires strenuous physical effort on behalf of the rescuer, especially when coupled with chest compressions, making it difficult to perform effectively for extended periods of time. Third, it is difficult, even for experienced medical personnel, to deliver consistent breaths using mouth-to-mouth, which may have deleterious consequences for the patient.
Prior art methods have attempted to overcome the risk of disease transmission during mouth-to-mouth by developing various devices that create a physical barrier between the rescuer and the patient. However, many of these devices are not 100% effective in preventing disease transmission, may interfere with the delivery of a rescue breaths and do not overcome the farther disadvantages of mouth-to-mouth listed above.
One prior art solution that eliminates the need for mouth-to-mouth altogether is the bag valve mask (BVM) resuscitation system or Ambu bag. Bag systems generally consist of some form of squeezable bag (such as a bulb or bellows) connected to a mask. When the bulb or bellows is contracted, air is forced into the patients airway, delivering a breath. An example of such a bag resuscitation system is described in U.S. Pat. No. 4,774,941 to Cook et al. Although bag systems overcome some of the drawbacks of the mouth-to-mouth technique, they have several disadvantages. First, although they may be less tiring than mouth-to-mouth techniques, constant squeezing of the bag requires substantial effort, and the person delivering emergency breathing can still quickly become fatigued. Second, as each person squeezes the bag in a different manner and as it is impossible for even an advanced user to make each squeeze identical, bag systems cannot be used to deliver consistent emergency breathing. As such, dangerously small or large breaths may be delivered, both of which may put the patient's life at risk. Further, inconsistent delivery of breaths over an extended period may cause damage to the patient's airway.
A few automatic ventilator/resuscitator systems are known in the art. However, these devices are typically designed as ventilators, meaning that they deliver continuous mechanical breathing. Also, the systems known in the art may not be portable, may have complicated control systems or may not provide the type of feedback that allows for their use by a member of the general public. Many of the ventilator/resuscitator systems known in the art are also very complicated to manufacture and use, making their widespread dissemination impractical. Further, as many of these devices function primarily as ventilators, their use is highly regulated and restricted in most countries around the world, making it nearly impossible for them to be available to the general public. See, for example, the FDA's Draft Guidance for Emergency Resuscitators dated July 1995 (available at http://www.fda.gov/cdrh/ode/500.pdf) and international standards ISO 10651-4 and ASTM 110-90.
U.S. Pat. No. 5,398,676 to Press et al. describes a ventilator with various modes, including an automatic CPR mode. However, the complexity of the device, its lack of feedback for the user and its primary function as a ventilator make its widespread use by the general public impracticable.
U.S. Pat. No. 5,520,170 to Laswick et al. describes an automatic resuscitator. However, the device offers no feedback to user to allow for tightly controlled delivery of emergency breaths, especially during CPR. The device detects breathing and switches to a demand mode if necessary. Because of the complexities of the Laswick device, and further because its mechanism of action is likely to cause it to be classified as a ventilator, the device is not suitable to widespread dissemination for use by members of the general public.
Both U.S. Pat. No. 4,651,731 to Vicenzi et al. and U.S. Pat. No. 4,941,469 to Adhan et al. describe portable ventilator systems. Because these systems are ventilators, they have the same drawbacks as described above. Further, these devices provide a backpressure in the patients airway during exhalation known as Positive End Expiratory Pressure (PEEP), which is not recommended during delivery of emergency breathing by the American Heart Association (see Circulation, 2005: 112: IV-48).
Accordingly, there is a need in the art for a portable resuscitation device that can not only be widely disseminated to the general public, but can further be used by members of the general public without medical training to provide safe and efficient emergency breathing.